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Tsetse control, agricultural expansion and environmental change in NigeriaBourn, David January 1983 (has links)
A brief account of the history of government organised tsetse and trypanosomiasis control in Nigeria is presented, and major features of the tsetse eradication programme are summarised. The achievements are considered in the context of widespread environmental change, brought about by an increasing human population, and a long term process of agricultural expansion, which have resulted in an overall reduction in natural tsetse habitats and hosts, and led to a general decline in tsetse populations. A comparison of two areas, one within, and the other outside the tsetse eradication zone, showed that they had both experienced similar rates of change in land use, and available information indicated that human and cattle populations had also increased at similar rates. The present day distribution and abundance of tsetse and cattle in a region of the Nigerian sub-humid zone, not yet reached by the tsetse eradication programme, are described. In the virtual absence of wildlife, abundance of cattle, and concentration of the two riverine tsetse species at crossing points, it was concluded that tsetse were largely dependent on cattle and/or man for their survival. The low density of riverine tsetse populations, their restricted distribution and their low infection rates, combined with Fulani herd management practices, which limited the period of contact between tsetse and cattle, indicated that under the prevailing conditions, trypanosome challenge was likely to be very low. It is suggested that this situation was typical for many areas within the sub-humid zone, and that in the future, similar conditions are likely to become even more widespread. It is concluded that, whilst government trypanosomiasis control programmes must have contributed to the general decline of the disease which has taken place, the environmental context within which they were mounted, has changed significantly. Over the past fifty years human population has almost certainly increased three or four fold, and the extent and intensity of both farming and hunting have increased commensurately. This has resulted in an overall reduction in natural tsetse habitats and hosts, which has led to a decline in vector populations. It is argued that this, together with a trend for Fulani and their cattle to become more sedentarised, has brought about a fundamental change in the balance of relationships in the vector-host-disease complex, which has favoured the development of appropriate immune responses in Fulani cattle, and the selection of less pathogenic strains of trypanosome.
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An investigation of the utility of remotely sensed meterological satellite data for predicting the distribution and abundance of the tsetse fly (Diptera: Glossinidae)Hay, Simon Iain January 1996 (has links)
This thesis investigates the potential contribution of data from the Advance Very High Resolution Radiometer (AVHRR) on-board the National Oceanic and Atmospheric Administrations (NOAA) polar-orbiting meteorological satellites and data from the High Resolution Radiometer (HRR) on-board the Meteosat geostationary meteorological satellites for predicting the distribution and abundance of the tsetse fly (Diptera: Glossinidae) in Africa. The images were processed to produce a range of monthly land surface temperature, atmospheric moisture and rainfall indices for the period 1988 to 1990. The performance of these indices, derived from several different methods, was tested using meteorological records collected during these years at stations across continental Africa and the most accurate used to form a refined dataset for subsequent analysis. The time-series of these land surface temperature, atmospheric moisture and rainfall indices and a range of Spectral Vegetation Indices (SVI) were subject to temporal Fourier analysis to parameterise the seasonal variation in these variables. These data, in combination with elevation information from a digital elevation model (DEM) were used to predict the land-cover of Nigeria determined independently by an aerial survey in 1990. The Normalised Difference Vegetation Index (NDVI) performed best and so was used in combination with the satellite proxy meteorological and DEM data to predict the distribution and abundance of eight tsetse fly species in Cote d'lvoire and Burkina Faso, West Africa. The results are discussed in relation to the ecology of the different tsetse species. Conclusions are then drawn on the potential of such meteorological satellite data for remote tsetse fly population surveillance and, in the wider context, to the study and control of arthropod vectors of disease.
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Proteomic and immunochemical study of the tsetse fly 'Glossina morsitans morsitans' midgut and salivary glandHaddow, Jody Daniel. 10 April 2008 (has links)
No description available.
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Variability among individuals and populations : implications for arthropod physiologyTerblanche, Jonathan Steed 04 1900 (has links)
Dissertation (PhD)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: Within arthropods, inter-individual and inter-population variation is generally poorly explored for
physiological parameters. Such physiological variability is important, as it can provide insight into
the capacity for evolutionary adaptation and how animals may cope with anthropogenic climate
change. Insect vectors of human and animal diseases, such as tsetse flies (Diptera, Glossinidae)
which carry trypanosomes, are of particular interest. Predictions of tsetse fly (Glossina spp.) range
expansion, possibly paralleled by increased disease occurrence, have been made under future
climate scenarios. Moreover, since there are generally strong relationships between abiotic variables
(e.g. temperature and moisture availability), population dynamics, distribution and abundance,
determining the physiological mechanisms influencing such relationships has utility for predictive
modelling of spatial and temporal changes in tsetse fly distributions. I investigated physiological
variation among individuals and populations, focusing mainly on Glossina spp. but using other
arthropods to address certain issues. Specifically, I show the following: i) metabolic rate is
repeatable (intra-class correlation coefficient) within individuals, and may be influenced by several
factors such as age, gender, body mass and pregnancy; ii) while metabolic rate is repeatable within
individuals, it remains unaltered with acclimation to laboratory conditions from field collection; iii)
within a population, metabolic rate-temperature relationships are surprisingly invariant among
physiological states such as age, gender, feeding status, pregnancy and temperature acclimation; iv)
the magnitude of the effect of temperature acclimation differs among traits, in that upper thermal
tolerances respond less than lower thermal tolerances, while metabolic rate responds to heat but not
to cold. Water loss rate is relatively unresponsive to either treatment; v) plasticity can account for
most inter-population variation in physiological traits related to climatic stress resistance (e.g.
thermotolerances and desiccation rates) in the natural environment; vi) adult physiological
performance responds differently to developmental and adult acclimation, such that marked traitspecific
variation occurs, and combinations of both developmental and adult plasticity can result in
further alteration of adult performance. These results have implications for the evolution of stress
resistance to abiotic factors in these and other arthropods. I conclude by discussing the potential
physiological patterns linking population dynamics and abiotic factors, with particular reference to
tsetse flies. / AFRIKAANSE OPSOMMING: Binne arthropoda, is tussen-individu en tussen-bevolking variasie in die algemeen sleg bestudeer vir
fisiologiese parameters. Hierdie fisiologiese variasie is belangrik want dit kan insig gee in die mate
van evolusionêre aanpassing en hoe diere antropogenies klimaatsverandering kan hanteer. Dit is
veral belangrik in die geval van insekte wat mens- en diersiektes kan dra, soos tsetse vlieë (Diptera,
Glossinidae) wat trypanosome oordra. In die geval van tsetse vlieë (Glossina spp.) is voorspellings
vir verhoogde verspreiding, en gevolglik verhoogde siekte voorkoms, gemaak onder toekomstige
voorkoms klimaat senario’s. Verder, aangesien daar in die algemeen sterk verwantskappe tussen
abiotiese parameters (bv. temperatuur en water beskikbaarheid), bevolkingsdynamika, verspreiding
en voorkoms is, is die bepaling van die fisiologiese meganisme, wat ‘n invloed het op hierdie
verwantskappe, nuttig vir die voorspelling van tsetse oor spasie en tyd. Hier, met hoofsaaklik die
gebruik van Glossina spp., maar ook ander arthropoda wanneer dit nodig is, word navorsing wat
fisiologiese variasie tussen individue en bevolkings aanspreel voorgelê. Spesifiek, word dit gewys
dat i) metaboliese tempo is herhaalbaar (intra-klas korrelasie koeffisient) binne individue, alhowel
metaboliese tempo kan beinvloed word deur faktore soos ouderdom, geslag, liggaamsmassa en
swangerskap, ii) terwyl metaboliese tempo binne individue herhaalbaar is, verander dit nie met
akklimasie na laboratorium toestande vanaf versameling in die veld, iii) binne ‘n bevolking
metaboliese tempo-temperatuur verwantskappe is verbasend eenders tussen fisiologiese toestande
soos ouderdom, geslag, voeding staat, swangerskap en temperatuur akklimasie, iv) die grootte van
die effek van temperatuur akklimasie verskil tussen eienskappe, en die boonste termiese limiete
reageer minder as laer termiese limiete, terwyl metaboliese tempo reageer op hitte maar nie koue
nie, en waterverlies tempo is relatief terughoudend tot enige temperatuur toestand, v) buigbaarheid
kan die meeste van inter-bevolkingsvariasie in fisiologiese eienskappe van klimaatstres
weerstandsvermoë (termiese toleransie en uitdrogingstempo) in die natuurlike omgewing verklaar,
vi) volwasse fisiologiese prestasie reageer verskillend op ontwikkelende en volwasse akklimasie,
soveel dat eienskap-spesifieke variasie kan voorkom, en ‘n kombinasie van beide ontwikkelende en
volwasse buigbaarheid ‘n verskillende volwasse prestasie tot gevolg kan hê. Hierdie resultate het
implikasies vir die evolusie van weerstandsvermoë tot abiotiese faktore in hierdie en ander
arthropoda. Hierdie tesis word afgesluit met ‘n bespreeking van die moontlikke fisiologiese patrone
wat bevolkingsdinamika en abiotiese faktore kan verbind, met ‘n fokus op tsetse vlieë.
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Impacts of climate change on tsetse (Diptera: Glossinidae) : water balance physiology and mechanistic modellingKleynhans, Elizabeth 12 1900 (has links)
Thesis (MScAgric (Conservation Ecology and Entomology))--Stellenbosch University, 2011 / ENGLISH ABSTRACT: Climate change will alter both temperature and moisture availability in the future and therefore will
likely affect vector borne disease prevalence. Organisms faced with changes in weather can respond
in a variety of ways and this complicates any predictions and inferences for these organisms with
climate change. Cause-and-effect links between climate change, insect vector responses, and
changes in risk of disease transmission are poorly established for most vector borne diseases. Tsetse
(Diptera, Glossinidae) are important vectors of trypanosome parasites posing a major threat to
human health and socio-economic welfare in Africa. Water balance plays an important role in
determining activity patterns, energy budgets, survival and population dynamics and, hence,
geographic distribution and abundance of insects. Glossina species occupy a wide range of habitats
in Africa and are notable for their desiccation resistance in xeric environments. Yet, whether or not
the different species, subgroups or ecotype groups differ in susceptibility to changes in weather
remain undetermined.
The first main focus of my thesis was to test the effects of climate change on water balance traits
(water loss rate, body water content and body lipid content) of adult tsetse flies. Four species from
xeric and mesic habitats were exposed to a range of temperature (20 – 30 °C) and relative humidity
(0 – 99 %) combinations. Water loss rates were significantly affected by measurement treatments,
while body water content, body lipid content and mass were less affected and less variable across
treatment combinations. The results provide support for mass-independent inter- and intra-specific
variation in water loss rate and survival times. Therefore, water balance responses to variation in
temperature and relative humidity are complex in Glossina, and this response varies within and
among species, sub-groups and ecotypes in terms of magnitude and the direction of effect change.
Secondly, I apply a mechanistic distribution model for G. pallidipes to predict potential population
responses to climate change. I validate the mechanistic model (NicheMapperTM) results spatially
and temporally using two methods. Both tests of the model showed that NicheMapper‟s predicted
resting metabolic rate has great potential to capture various aspects of population dynamics and
biogeography in G. pallidipes. Furthermore, I simulate the effect of phenotypic plasticity under
different climate change scenarios and solve for the basic reproductive number of the
trypanosomiasis disease (R0) under a future climate scenario.
This integrated thesis provides strong evidence for a general decrease in optimal habitat for G.
pallidipes under future climate change scenarios. However, it also provides strong support for a 1.85 fold increase in R0 based on changes in biting frequency as a result of higher predicted
metabolic rates in the future. This might suggest that the reduction in optimal habitat could be
outweighed by the increase in R0. The results demonstrate that an understanding of the
physiological mechanism(s) influencing vectors of disease with climate change can provide insight
into forecasting variation in vector abundance and disease risk. / AFRIKAANSE OPSOMMING: Die invloed van klimaatsverandering op die temperatuur en vog beskikbaarheid mag moontlik
insek-oordraagbare siektes in the toekoms beïnvloed. Organismes wat verandering in klimaat ervaar
kan op verskillende maniere reageer en daarom is voorspelling en afleidings van die reaksies op
klimaatsverandering nie eenvoudig nie. Boonop is die verband tussen klimaatsverandering, insek
reaksies en veranderinge in die oordragsrisiko van siektes onbekend vir die meeste insekoordraagbare
siektes. Tsetse (Diptera: Glossinidae) is belangrike draers van trypanosoom parasiete
wat 'n bedreiging inhou vir mensegesondheid en sosio-ekonomiese welsyn in Afrika. Waterbalans
speel 'n belangrike rol in die energiebondel samestelling, aktiwiteitspatrone, oorlewing en populasie
dinamika van insekte en, dus, die geografiese voorkoms en verspreiding van insekte. Glossina
spesies kom in 'n verskeidenheid habitatte in Afrika voor en is bekend daarvoor dat hulle weerstand
bied teen uitdroging in droё habitatte. Maar, die mate waartoe die verskillende subgroepe,
ekotiepegroepe en spesies kwesbaar is vir klimaatsverandering, is steeds onbekend.
Die eerste hooffokus van my tesis was om die uitwerking van klimaatsverandering op waterbalansrelevante
uitkomste (tempo van waterverlies, waterinhoud en vetinhoud) van volwasse tsetse vlieё
te bestudeer. Vier spesies van droë en klam habitatte is aan verskillende kombinasies van
temperatuur (20 – 30 °C) en relatiewe humiditeit (0 – 99 %) blootgestel. Die tempo van
waterverlies is betekenisvol deur die verskillende toetskombinasies beïnvloed, terwyl die waterinhoud,
vetinhoud en liggaamsmassa tot 'n minder mate beïnvloed is en minder gevarieer het tussen
die toetskombinasies. Die resultate toon bewyse vir gewigs-onafhanklike inter- en intraspesie
variasie in waterverlies tempo‟s en oorlewingstyd. Die waterbalans uitkomste op variasie in
temperatuur en relatiewe humiditeit is dus ingewikkeld in Glossina, en dit varieer binne en tussen
spesies, subgroepe en ekotiepe in terme van die graad en rigting van effek verandering.
Tweedens pas ek 'n meganistiese verspreidingsmodel toe vir G. pallidipes om die moontlike
populasiereaksies met klimaatsverandering te voorspel. Ek toets die antwoorde van die model
(NicheMapperTM) oor tyd en skaal op twee verskillende maniere. Beide toetse het aangedui dat die
NicheMapper voorspelde rustende metaboliese tempo die verskillende aspekte van G. pallidipes
populasie dinamika en biogeografie goed beskryf. Ek simuleer die uitkomste van die fenotipiese
veranderbaarheid van G. pallidipes onder „n verskeidenheid klimaatsverandering-uitkomste, en los „n model van die basiese ommekeer van trypanosomiasis (R0) op onder 'n klimatsverandering
situasie in die toekoms.
Hierdie geïntegreerde tesis toon sterk bewyse dat die optimale habitat van G. pallidipes verminder
met klimaatsverandering. Dit toon egter ook bewyse vir 'n 1.85 keer toename in R0 gebasseer op 'n
verhoging in die frekwensie van bytgeleenthede weens die hoër voorspelde metaboliese tempo van
die vlieë in die toekoms. Laasgenoemde stel voor dat die afname in optimale habitat moontlik deur
'n toename in R0 oorheers sal word. Die resultate demonstreer dat beter begrip van die fisiologiese
meganisme(s) wat parasiet-draers beïnvloed verdere insig kan voorsien in die toekomstige
voorspelling van draer teenwoordigheid en siekte waarskynlikheid.
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Investigation into the ecology of trypanosomiasis in the Lungawa Valley, ZambiaAnderson, Neil Euan January 2009 (has links)
The Luangwa Valley is recognised as a focus of endemic infection with human sleeping sickness caused by Trypanosoma bruceirhodesiense. Extensive infection of the wildlife population with many species of trypanosome has been identified and livestock keeping is almost non-existent due to losses from trypanosomiasis and predation by wild animals. The aim of this study was to investigate the ecology of trypanosomiasis in this mult-host wildlife community, relatively free from anthropogenic influences. Particular focus was to be applied to the role of common warthog, phacocoerus aethipicus, within the reservoir community. The thesis initially reviews the history of protected area management in the Luangwa Valley. Remotely sensed imagery is then used in a study of the vegetation units of Luambe National Park. A supervised classification algorithm utilising fuzzy logic is used to generate a land cover classification of the part with an overall accuracy of 71%. Surveys of the tsetse and wild mammal population in Luambe national park are then presented. Data collected from the tsetse survey are analysed using generalised linear models with mixed effects to investigate factors influencing the trypanosome prevalence in tsetse, as well as the distribution and apparent density of tsetse. The density of tyhe host mammal population is assessed using distance sampling techniques and the distribution of warthog burrows mapped. Finally, a cross-sectional survey of trypanosome prevalence in the wild animal population of the Luangwa Valley is described, using novel molecular techniques for diagnosis. Risk factors for infection are analysed using logistic regression analysis and the host distribution for each trypanosome species described.
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Ecology of a vector-borne zoonosis in a complex ecosystem : trypanosomiasis in Serengeti, TanzaniaAuty, Harriet K. January 2009 (has links)
Unravelling the complexities of a disease with multiple wildlife host and multiple tsetse vector species is no easy task. After over a century of field observations, experimental studies, anecdotal evidence and conjecture, the role of wildlife in the transmission of trypanosomes is still unclear. Recently, however, frameworks used in the studies of other vector-borne diseases with wildlife reservoirs showed that not only is it possible to understand transmission, but that spatio-temporal predictions of human disease risk and targeted control are realistic aims, even in such complex systems. This thesis explores the epidemiology of human African trypanosomiasis (HAT) in the Serengeti-Mara ecosystem in Northern Tanzania, where recent cases in tourists have highlighted the disease as a public health and economic concern. Assessment of the prevalence of trypanosome infections in different wildlife species is the first step in investigating the relative importance of different species in disease transmission. Identification of trypanosomes relies on sensitive and specific diagnostic tests. Polymerase chain reaction (PCR) protocols based on interspecies differences in the length of the ribosomal internal transcribed spacer (ITS) regions have been widely used in livestock to identify multiple trypanosome species in one PCR reaction. This study represents the first assessment of these protocols on blood samples collected from wildlife. Clonal sequence analysis of PCR products revealed a large range of trypanosomes circulating in wildlife, including Trypanosoma congolense, Trypanosoma brucei, Trypanosoma simiae Tsavo, Trypanosoma godfreyi and Trypanosoma vivax. In addition sequences similar to known sequences, termed Trypanosoma simiae-like and T. vivax-like trypanosomes, may reflect further diversity. However, further characterisation is needed before ITS protocols can be used widely for epidemiological studies in wildlife. The prevalence of T. brucei s.l. and T. congolense varied widely between species. This variation was predominantly explained by taxonomic classification, suggesting intrinsic differences in response to trypanosomes. Trypanosoma brucei rhodesiense, the subspecies responsible for HAT, was identified in lion, hyaena and reedbuck. Age significantly affected the prevalence of T. congolense in lion and hyaena, with the highest prevalence in subadults. The lack of statistically significant differences in prevalence between animals sampled live or after death confirmed that post-mortem sampling provides a method for increasing sample sizes in wildlife studies. The complex relationship between tsetse density and prevalence of trypanosome infections illustrated the difficulties of assessing data from diverse ecosystems with many potential confounding factors. A cross-sectional study of Glossina swynnertoni and Glossina pallidipes, the main tsetse species in Serengeti, highlighted the difficulties of integrating the results of microscopy and PCR to generate meaningful measures of the prevalence of transmissible T. brucei infections for epidemiological studies. However, PCR results suggested that G. pallidipes may be more important as a vector of T. brucei s.l. than has been previously recognised. Spatial variation in both tsetse density and the prevalence of trypanosome infections suggests human disease risk is heterogeneous. The results of this study, along with relevant literature, are considered within the context of frameworks used for other vector-borne diseases and the implications for disease management discussed.
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Vectors and transmission routes of animal trypanosomiasis on the Jos Plateau north central NigeriaOlaniyan, Oluwashola January 2016 (has links)
Tsetse flies, Glossina species, are the biological vectors of Trypanosoma species which cause animal African trypanosomiases (AAT) in livestock (especially cattle) in sub-Saharan Africa. This disease is often fatal without treatment and negatively impacts on rural, agricultural and economic development. On the Jos Plateau, north central Nigeria, AAT was historically of little significance due to the presumed absence of tsetse and Fulani pastoralists were encouraged to settle there. But over the last 30 years, the disease has become widespread and highly prevalent in the area. This has been attributed to the expansion of tsetse on the plateau, frequent migrations of cattle to areas with higher tsetse densities and the presence of other biting flies which serve as mechanical vectors. In the current study, the presence and abundance of tsetse was determined in selected villages using biconical tsetse trap surveys. The low number of flies trapped suggests that tsetse expansion has been very limited within the plateau but the fact that trypanosome DNA was present in over half of these flies implicates them in AAT transmission. The migration of a herd of cattle was also tracked and during the period, blood samples were collected from the cattle and examined for trypanosomes using molecular techniques. Despite prophylactic treatment and deltamethrin sprays, results showed that a significant proportion of the animals (52%) had become infected with T. vivax over the migration period. Tsetse flies (G. palpalis) were also slightly more abundant in some of parts of the migration area. Potential mechanical vectors (Stomoxys spp. and Tabanidae) were trapped and results obtained from the examination of their mouthparts for trypanosomes indicate their involvement in transmission. However, it is difficult to make any definite conclusions about their overall contribution which is thought to be minimal and more studies are needed to clarify their significance. It is concluded that trypanosomiasis risk from tsetse on the Jos Plateau is currently low and seasonal migration appears to be the main driver of AAT transmission by exposing cattle to more tsetse for longer periods. Other biting flies may play a limited role which remains undetermined. Continued monitoring of cattle and tsetse across the plateau over the next few years is important and the careful use of trypanocides and insecticide treated cattle is recommended as an appropriate control strategy.
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A comparative investigation into the indigenous land management practices between Tsetse and Miga communities in the North West Province (Molopo District) / Yvonne MogopaMogopa, Yvonne January 2005 (has links)
The study investigated indigenous land management practices in the North West
Province with special reference to Miga and Tsetse villages. The study found that the
apartheid forced removal policies had a great impact on the socio-economic and cultural
life of the communities in the two study villages. The communities were resettled in a
new harsh environment in which they encountered. various problems with adaptation.
The land management practices in Miga and Tsetse villages were different from the
traditional farming practices in their places of origin in the then Western Transvaal,
where they were self-reliant. The new farming practices in Miga and Tsetse are based
on modern agricultural land use system, which include the use of modern equipment
and other inputs. Most of the community members cannot afford them due to high levels
of unemployment. Moreover, given the arid conditions of the area, the new farming
practices depend on availability of rain. The policy strategies and projects instituted and
implemented by both the Bophuthatswana government and the North West Provincial
government did not benefit the two communities much. Lack of funds and dependency
on government funds made the projects unsustainable.
The study recommended that since the Miga and Tsetse Communities have access to
land for farming, the North West Provincial Department of Agriculture should put more
emphasis on promoting and improving indigenous farming methods by incorporating
them into the provincial agricultural development strategies. This is due to the fact that
these practices are sustainable and affordable to the local communities. They are
adaptable and tuned to the needs of people. Also, they pertain to cultural values of the
communities. Moreover, the current poverty situation in Miga and Tsetse villages
necessitates the great need for the communities to initiate other income generating
ventures beside agriculture. The government should provide the communities with the
necessary support including capacity building to ensure the sustainability and success
of these projects / (M.Soc.Sc.) North-West University, Mafikeng Campus, 2005
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An individual-based model of tsetse fly populations dynamics : modelling an extensive mark-release-recapture experimentFerreira, Roux-Cil 04 1900 (has links)
Thesis (MComm)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Tsetse flies (Glossina spp), native to mid-continental Africa, are the vectors
of trypanosomes that causes human (sleeping sickness) and animal (nagana)
trypanosomiasis. Vector control plays a major role in alleviating the burden
of the disease. Mathematical models of tsetse population dynamics provide
insights into how best to manage these control efforts.
A major mark-recapture experiment, carried out in Zimbabwe, provided
valuable information on tsetse population dynamics, but the analyses so far
published could be improved on because not all of the information available
on the marking procedure was used.
We have constructed an individual-based model that follows the life of individual
tsetse flies, their progeny and, in particular, the sequence of occasions
on which individual flies were captured and given distinctive marks. We have
access to comprehensive data from the tsetse fly mark-release-recapture experiment
carried out on Antelope Island, Lake Kariba, Zimbabwe. In order
to calibrate or validate the model, we model both the growth of the introduced
tsetse population and the mark-recapture process. We have compared
the model outputs to the original data and recommend processes that may be
followed for model calibration.
It is possible to construct an individual-based model that adequately models
tsetse fly populations. Whereas the focus of this study has been on modelling
the mark-recapture study, the individual-based model could also be used
in more general settings to model the growth, and reduction in fly numbers,
changes in age structure, species and gender ratios and the acquisition of trypanosome
infections by individual flies. This model can thus be used to investigate the effect of various factors on tsetse fly and trypanosome, population
dynamics as well as on the performance of various control techniques effecting
fly mortality and disease transmission. / AFRIKAANSE OPSOMMING: Tsetsevlieë (Glossina spp), inheems aan sentraalkontinentale Afrika, is die draers
van trypanosomen wat trypanosomiasis by die mens (slaapsiekte) en by
diere (nagana) veroorsaak. Die beheer van draers speel 'n belangrike rol om
die las wat die siekte veroorsaak, te verlig. Wiskundige modelle van tsetse bevolkingsdinamika
bied insigte oor hoe om beheerpogings die beste te bestuur.
'n Belangrike merk-hervang eksperiment, wat in Zimbabwe uitgevoer is,
bevat waardevolle inligting oor tsetse bevolkingsdinamika. Die ontleding daarvan,
wat tot dusver gepubliseer is, kan egter verbeter word aangesien nie al
die inligting beskikbaar in die merkprosedure, gebruik is nie.
Ons het 'n individu-gebaseerde model saamgestel wat die lewens van individuele
tsetsevlieë en hul nageslagte volg, in besonder die volgorde waarop
individuele vlieë gevang en herkenbaar gemerk is. Ons het toegang tot omvattende
data van die tsetsevlieg merk-vrylaat-hervang eksperiment wat uitgevoer
is op Antelope Eiland, Karibadam, Zimbabwe. Ten einde die model te kalibreer
of om die model se geldigheid te bevestig, modelleer ons beide die groei
van die ingevoerde tsetse bevolking en die merk-hervangs metode. Ons vergelyk
die modeluitsette met die oorspronklike data en beveel prosesse aan wat
gevolg kan word om die model te kalibreer.
Dit is moontlik om 'n individu-gebaseerde model saam te stel wat tsetsevliegbevolkings
voldoende moduleer. Terwyl hierdie studie die modellering
van die merk-hervang data bestudeer, kan die individueel-gebaseerde model
ook gebruik word in meer algemene gevalle vir die modellering van die vermeerdering
en vermindering in vlieë getalle, veranderinge in die ouderdomstruktuur,
spesies en geslagverhoudings en die verwerwing van trypanosomen
infeksies deur individuele vlieë. Hierdie model kan dus gebruik word om die
effek te ondesoek van verskeie faktore op die tsetsevlieg en trypanosomen, populasiedinamiek
sowel as die prestasie van verskillende beheertegnieke rakende
vliegsterftes en siekte-oordrag.
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